Many types of hand tools such as knives and multi tools incorporate folding mechanisms that allow an implement to be moved between a folded position in which the implement is safely stowed in the tool handle, and an extended position in which the implement is ready for work. One typical example of such a folding tool is a knife having a folding blade. The knife handle typically has two opposed handle portions defining a blade-receiving groove. A blade pivots on a shaft attached to the handle such that in a folded position the blade is stowed with the cutting portion of the blade retained safely in the groove, and such that in an extended position the blade is extended away from the handle, ready for use.
To increase the safety of folding tools such as knives, many such tools incorporate locking mechanisms of one type or another. When the knife blade pivots into the open position, it's pivotal movement is stopped with a blocking mechanism such as a transverse blade stop pin housed in the handle. Many kinds of knives include a locking mechanism that prevents the blade from unintentionally pivoting back from the open into the closed position.
There are many types of locking mechanisms. One common type is a “liner lock.” This kind of mechanism relies upon a resilient lever formed as part of a handle liner. When the blade is pivoted to the open or extended position, the resilient lever engages a cooperatively formed shoulder on the blade and thereby locks the blade in the open position.
There are other types of blade locks in addition to the liner locking mechanisms just described but there is a need therefore for improved locking mechanisms for folding hand tools.
The present invention relates to a hand tool—typically embodied as a knife—that incorporates a lock mechanism for securely locking the implement such as a blade in the open position, and for releasing the lock to allow the implement to be folded back into the closed position. The locking mechanism incorporates a safety mechanism that prevents the blade engaging lock from becoming disengaged unintentionally.